Remove flash_activity that was stealing focus to LED 0

src/app_task.cpp

@@ -46,9 +46,6 @@ void AppTask::process_midi_event(const MidiEvent& event) {
     Serial.printf("[APP] MIDI IN: Type=%d Ch=%d Data1=%d Data2=%d\n",
                   event.type, event.channel, event.data1, event.data2);
     
-    // Flash LED 0 white briefly on ANY MIDI input - visual activity indicator
-    led_driver->flash_activity();
-    
     if (event.type == MidiEvent::SYSEX) {
         // Cin is encoded in channel for SYSEX packets
         uint8_t cin = event.channel;